Study Design. This study investigated the subaxial cervical pedicles from C3 to C7 to provide information for accurately transpedicular screw fixation in this region. Objective. This study was evaluated the morphology of the subaxial cervical pedicle to determine the size and trajectory of screw fixation. Summary of Background Data. Cervical vertebrae are an important structure to protect the neurovascular structure. The cervical spine surgery using screw fixation is an effective method to treat the cervical spine instability. There have been many research morphological data of subaxial cervical vertebrae. However, no studies have reports on dried cervical vertebrae of Thai's people. Methods. The measurement was conducted in 130 dried cervical vertebrae (C3–C7), including 61 males and 69 females. The measurement parameters were pedicle width (PW), pedicle length (PL), pedicle height (PH), pedicle axis length (PAL), pedicle transverse angle (PTA), and pedicle sagittal angle (PSA), which determined using ImageJ software. Results. The results of morphological data of C3 to C7 was found that the mean of PW, PL, PH, PAL, PTA, and PSA that obtained from male were significantly higher than female excepted for PL (C7) and PTA (C3, C5). Except for the C6 PW, C3 PL, C4 to C5 to C7 PTA, and C4 PSA, there were no significant differences of these parameters between male and female. Conclusion. The appropriate pedicle screw size is 4.0 mm for C3 and C4, and 4.5 mm for C5 to C7. The results of this study are the useful information for cervical spine fixation while prevent the vascular and neurological injuries from the large screw causing pedicle breakage. Level of Evidence: 3

<p>  </p> <p><strong>Key Findings:</strong> The aortic bifurcation can be predetermined using the prediction model. The left common iliac artery (LCIA) was longer, more vertical, and closer to the lumbar spine than the right common iliac artery (RCIA). The formula of the diameter of the aorta, RCIA and LCIA is file:///C:/Users/ortho/AppData/Local/Temp/msohtmlclip1/01/clip_image002.png (D, diameter; a, aorta; r, RCIA; l, LCIA). The formula for the angle of aortic bifurcation is file:///C:/Users/ortho/AppData/Local/Temp/msohtmlclip1/01/clip_image004.png. Surgeons can use these formulas to predict and solve the problem when dealing with these arteries.</p>

<p>  </p> <p><strong>Key Findings:</strong> The aortic bifurcation can be predetermined using the prediction model. The left common iliac artery (LCIA) was longer, more vertical, and closer to the lumbar spine than the right common iliac artery (RCIA). The formula of the diameter of the aorta, RCIA and LCIA is file:///C:/Users/ortho/AppData/Local/Temp/msohtmlclip1/01/clip_image002.png (D, diameter; a, aorta; r, RCIA; l, LCIA). The formula for the angle of aortic bifurcation is file:///C:/Users/ortho/AppData/Local/Temp/msohtmlclip1/01/clip_image004.png. Surgeons can use these formulas to predict and solve the problem when dealing with these arteries.</p>

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